Conventionally, a module for storing and conveying fragile and heavy thin panels such as solar panels stacked in the vertical direction so as not to contact one another has been used. Patent Document 1 and Patent Document 2 disclose examples of the module.
This module includes a support surface and a molded member. The support surface supports a thin panel from below. A peripheral edge portion of the thin panel is sandwiched by a frame body. The molded member is coupled with the support surface, extends outwardly from the support surface, and transmits the weight of the thin panel in the vertical direction. The molded member includes a recess or a protrusion on each of the upper portion and the lower portion. The recess and the protrusion fit each other. This module is placed at each of the four corners of the thin panel via the frame body so as to rest on each support surface of this module via the frame body. Then, in each corner, the recess at the lower portion of the molded member in a new module fits the protrusion at the upper portion of the molded member in a module that has been already disposed. Similarly, the next thin panel is supported by four modules. Accordingly, the thin panels are allowed to be stacked in the vertical direction in a non-contact manner. However, the following technical problems arise in this module.
Firstly, it is difficult to stack a plurality of the thin panels in the vertical direction stably because a positioning portion for the thin panel and a load transmitting portion for the thin panel are not separated with each other. This problem will be described more specifically as follows. The upper portion and the lower portion of the molded member each form a load transmitting surface. The recess and the protrusion are provided on the upper portion and the lower portion, respectively. The recess on the lower portion of the upper module fits the protrusion on the upper portion of the lower module. This allows for positioning of the upper module in the horizontal direction relative to the lower module. Accordingly, it is difficult to sufficiently ensure load transmitting areas on the upper portion and the lower portion of the molded member because the protrusion and the recess exist. This makes it difficult to stably stack the plurality of the thin panels in the vertical direction.
Secondly, the module requires a considerable amount of material, and this leads to increase in cost because a support portion for the thin panel and the positioning portion for the thin panel are separated with each other. This problem will be described more specifically as follows. As illustrated in FIG. 7 of Patent Document 1, a thin panel without a frame is sandwiched between and supported by a pair of bars 14. Using a cylinder portion 13, which is additionally disposed outside of the pair of bars 14, a dowel 6, which is disposed on the lower portion of the cylinder portion 13 of the upper module, fits a void 8, which is disposed on the upper portion of the cylinder portion 13 of the lower module. This allows for positioning of the upper module in the horizontal direction relative to the lower module. Accordingly, a certain amount of diameter expansion of the cylinder portion 13 is required to stably stack the plurality of thin panels in the vertical direction because the support portion for the thin panel and the load transmitting portion for the thin panel are separated with each other and the cylinder portion 13 particularly also serves as the load transmitting portion. This correspondingly requires an extra amount of material.
Thirdly, it is difficult to efficiently stack the plurality of thin panels in the vertical direction. More specifically, for example, in the case where the thin panels are stacked with the modules on the top surface of a pallet in order to convey the stacked thin panels by a forklift truck, the thin panels cannot be stacked unless the modules are preliminarily positioned at a position corresponding to each of the four corners of the thin panel on site, on the top surface of the pallet. This problem will be described more specifically as follows. Each thin panel is placed on the support surface of the module at each of the four corners and is supported from below. Accordingly, the thin panel cannot be supported unless the support surface of the module is preliminarily prepared at each corner in advance. In this respect, it is difficult to place the module at each of the four corners of the plurality of thin panels in advance and then stack the thin panels, which has the modules at the four corners, on the top surface of the pallet. If one dares to take these steps, stability of the modules stacked in a columnar shape may be degraded when four modules attached to the thin panel are stacked at the same time on the modules, which are already stacked in a columnar shape at each corner on the top surface of the pallet, because each of the modules is not fixed to the corresponding corner portion of the thin panel. This might cause collapse of the modules in a columnar shape depending on the circumstance.
Fourthly, the protection for the thin panels is not sufficient especially when the thin panels with frames are stacked in the vertical direction. This problem will be described more specifically as follows. When the thin panels are stacked or while the thin panels are being stacked, the frame body may be pulled out from the module, and the thin panel and the frame body may together be removed from the module. This may cause damage of the thin panel, and may cause breakage of the thin panel depending on the circumstance. More specifically, as illustrated in FIG. 6 and FIG. 7 of Patent Document 1, when the thin panels are stacked or while the thin panels are being stacked, the thin panel and a frame profile 10 may together be removed from the module because inward movement of the frame profile 10 from the module, which is placed on a panel section 4, is not restricted. In contrast, as for the type illustrated in FIG. 4 of Patent Document 1, inward movement of the frame profile 10 from the module, which is placed on the panel section 4, is restricted by a border section 5, which projects upward from the inner edge of the panel section 4. However, this additionally requires the border section 5 and leads to increase in cost for forming the module.
Patent Document 1: JP-A-2006-32978
Patent Document 2: JP 55-7790 U